In polishing the surface of a substrate, it is often advantageous to monitor the polishing process in situ. One method of monitoring the polishing process in situ involves the use of a polishing pad having an aperture or window. The aperture or window provides a portal through which light can pass to allow the inspection of the substrate surface during the polishing process. Polishing pads having apertures and windows are known and have been used to polish substrates, such as semiconductor devices. For example, U.S. Pat. No. 5,605,760 (Roberts) provides a pad having a transparent window formed from a solid, uniform polymer, which has no intrinsic ability to absorb or transport slurry. U.S. Pat. No. 5,433,651 (Lustig et al.) discloses a polishing pad wherein a portion of the pad has been removed to provide an aperture through which light can pass. U.S. Pat. Nos. 5,893,796 and 5,964,643 (both by Birang et al.) disclose removing a portion of a polishing pad to provide an aperture and placing a transparent polyurethane or quartz plug in the aperture to provide a transparent window, or removing a portion of the backing of a polishing pad to provide a translucency in the pad.
Still, there remains a need for effective polishing pads comprising translucent regions, as well as methods for the production and use of such polishing pads. The invention provides such a polishing pad and methods of production and use. These and other advantages of the present invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.